At&t Bell Laboratories

American Telephone & Telegraph Co., At&t Bell Laboratories

Kevin D Kolwicz

Che-Tsung Chen

Gilbert L Mowery, Jr

Chin-Jen Lin

Won J Yoon

Integrated circuits having a large number of transmission gate logic stages have been found to draw a large current surge on power-up. This is due to the floating input node of complementary inverters causing current to flow briefly before clock pulses arrive. The present invention provides a DC voltage on the gates of the pass transistors until the system clock pulses arrive, thereby eliminating the floating node. An optional periodic window may be generated to examine the system clock after power-up, to detect a loss of clock condition.

Dynamic CMOS current surge control

A new technique for forming CMOS custom logic circuits is disclosed wherein standard cells (10,12,14) are used and the prior art technique of field oxide isolation (16) is replaced with transistor isolation (68-71). That is, the boundaries (18,20,22,24) between the cells are formed by transistors that are permanently 'off', i.e., tied to the positive or negative voltage supply, depending on whether the transistors are p-channel or n-channel devices, respectively. Therefore, instead of having to deposit separate p+ and n+ source/drain diffusions for each cell, as in the prior art, a single p+ diffusion strip (60) and a single n+ diffusion strip (62) are utilized, where the polysilicon mask of both the logic and isolation transistors defines the cell sizes. Thus, the p+ and n+ diffusions become generic steps which do not vary from circuit to circuit, decreasing the turnaround time associated with custom logic circuit layout and design.

Method of manufacturing a CMOS cell array with transistor isolation

The present invention relates to a glitch lockout circuit for a static random access memory (RAM) which prevents the writing or reading of incorrect data when a system clock is switched from a standard clock source to an alternate clock source. A dummy bit line is added to the memory arrangement which is always precharged during a first clock phase and discharged during a second clock phase. The state of the dummy bit line is latched with the first clock phase and is fed back to the clock generator to control the initiation of the second clock phase. Thus, if the dummy bit line stays low, the second clock phase will stay low and none of the RAM cells will be accessed.

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Allentown, PA, United States of America

Kevin D Kolwicz